Tire manufacture



Jam 28, 1941. g BOWERS mas umumc'rum FiledDec. 13. 193-1 3 Sheets-Sheet l INVENTOR. V QM 6'- {I'M 'BY' 'wa dflw V ATTORNEYS.

Jan. 28, 1941. A. c. BOWERS TIRE MANUFACTURE 'Filed Dec. 13; 1957 mmmz 3 Sheets-Sheet 2 INVENTOR. fi d 6? fiflww BY 64; mar/MW A momma ted Jan. 28, 1941 TIRE MANUFACTURE Application December 13, 1931, Serial No. 179,415

3 Claims. (01. 154-10) UNITED STATES- PATENT OFFICE EISSU APR 28 1942 My invention relates to the manufacture of pneumatic tires for automobiles and other vehicles, and, more specifically. to drum-built tires.

In accordance with prevailing practice, the

t tread and outer side walls of a tire are formed as an extruded strip of raw rubber which, cut to proper length, is applied upon and vulcanized to the usual fabric carcass of the tire.

The rubber of which the tread of a tire is m iorn'ied is essentially a relatively hard, wear-resitting rubber, while in the side walls of the tire the rubber is preferably a softer and more elastic rubber. For this reason it is customary to ioroo the extruded rubber strip, mentioned above,

it oi two different rubber compositions. The medial, relatively thick body portion oi! the stripthe portion thot forms the tread in the finished orticie-ds made oi a different rubber composition thou the relatively thin side margins of the- W strip that in the finished article provide the rub-'- her ioolneo for the side walls of the tire. The strip, so constituted, is manuiactured in a continuous cxtrudino process, and is cut into desired ienyths tor use in the construction of tires.

hit The i'uuchineo ior manufacturing such strips ore costly. They are elaborate extruding machines which simultaneously extrude two mixes or erodes oi uncured rubber into two strip sectiouo end, with uninterrupted continuity oi optiii erotiou, unite the sections-face to :locc and cittrude thelu iuto o. couipositestrip of desired iornl. huch mochiuet do not lend themselves reudily to odiuetroeut cud interchangeability oi extrud the heads ond dies, for the manufacture of strips til oi vorioue sizes.

in occordonce with my invention, the extrudiuo unochiue consists in two simple extruding unite, ouch unit extruding one of the strip-formioo sections oi rubber. .In continuous operation the too strip sections are led from the extruding units out occurately assembled and united. The invention consists both in method and in apparotuo, end by virtue oi the invention various sites oi strips may be readily made in a single ti iuotoiiotion oi the apparatus, it being understood thot in uhspeciaiized extruding machines or units oi the sort it use the extrudinz heads and dies inoy he chopped readily and quickly. Additionalit, the strips produced in my apparatus are more til uor our! structurally superior to those made hitherto. 1 in the accompanying drawings, I illustrate apporotus in which and in the operation oi which the invention is realized. Flo. I is a diagramto hustle view in plan 01' such apparatus: Fig. Ilia a fragmentary view, showing to larger scale certain parts of the apparatusin side elevation and other parts in vertical section, on "the plane'IL-II" 01' Fig. I; Figs. III and IV, are views in vertical section of particular parts of the apparatus to still larger scale, the plane of section of Fig. III being indicated at IIIIII and that of Fig. IV at IV--IV in Fig. I; Fig. V15 9. view in cross-section'of one oi the strip sections of which the composite strip is formed, and Fig. V1 is a slmi- 10 lot view of the other strip section.

Referring to the drawings, my apparatus includes two rubber-extruding units, each of welllmown simple construction. The two extruding units, .l and 2, are indicated fraomentarlly in 16 Fig. 1; they are spaced apart and in this-case are out of alignment, better to permit 01! orgonicotion with apparatus presently to be described. The extruding unit i, equipped with proper extruding head and dies, extrudes rubber in continuous length into a strip o. In the tinished article the strip it forms the tread oi the tire, and the rubber introduced to the machine i is oi such mix that when shaped ood vulcanized on the tire, it provides the essentiol tough, wear- :5 resisting tread. In the extrucliuo unit 2, rubber is extruded in continuous length into it strip b that in the finished article covers the side walls oi the tire. The rubber oi which strip h is termed is of such mix that, when opplied and vulcanized 3 to the carcoss OI a tire, it provides the desired sort end highly elastic coverioo on the side walls oi the tire. The strips or and h oreshown in cross-section in out. v and v1, respectively. The body of the 5 strip 1) includes two marginal portions ih that are relatively thin at their outer edges and increase in thickness towards the center of the strip, with maximum thickness reached in ridges to on the upper face oi the strip. The two mar- 43 olnal portions it of the strip are interconnected hy an intermediate web portion 3b; the web porticn 3b tolls away shorply in thickness from the ridges-2b and provides a thin-bottomed channel in which the strip a is compressed, with union 4.5 oi the two bodies. he presently will appear in greater detail, the body of the strip o is relatively thick with respect to the strip b, and its opposite sides to are tapered to sharply i'cathered edges to.

Tho-strips a and o are assembled and united in so continuous operation. Specifically, the strip a, advancing trom the extruding machine I, is by three endless conveyors 3, 4 and 5 carried to the' strip h advancing from machine 2. The advancinc strip h is supported and carried forward upon 55 a horizontal conveyor 6, arranged below the discharge end of conveyor 5. The conveyor 3 leads the strip a in horizontal course from the extruding machine I; the conveyor 4 carries the strip upward from conveyor 3, and feeds it downward to the conveyor 5 which, as shown in Fig. I, extends at right angles to the aligned conveyors 3 and 4. It is important to note that the nether surface (n) of the strip is leaving the machine I is the surface that in the assembled structure is united with strip b; in descending from the upper end of conveyor 4 to the conveyor 5 the strip a passes beneath a. roller 1, and in the course of such movement between conveyor 4 and roller I the body of the descending strip twists through 90 degrees; and thus the said surfacen of the strip passing beneath the roller 1 is presented downward upon the conveyor 5. At the discharge end of conveyor 5 the advancing strip again descends and again the descending body of the strip twists or turns through 90 degrees. Immediately above the surface of the conveyor 6 the strip passes beneath a roller 8 and into contact with the strip b advancing on such conveyor. The extruding units I and 2 and the conveyors of the system operate at such speed that the two strips a and b advance beneath the roller 8 at uniform velocity, and are assembled in the manner indicated in Fig. III, with the surface 11 of the strip a meeting the upper surface of the strip b between the ridges 2b, 2b.

Manifestly, the strips must be accurately centered with respect to one another, and to such end I secure the roller 8 against axial displacement in a stationary frame I 8 that bridges the conveyor, as shown in Fig. III. At a substantial interval above the roller 8, I mount a roller l9 in the frame, and between the two rollers I provide grooved wheels 2|) that engage the opposite edges of the descending strip a and insure accuracy of alignment of the two advancing and meeting strips. As may be' perceived in Fig. II, the roller l5 serves to take the twist out of the strip moving downward from the conveyor 5, and guides the descending strip into a plane that is normal both to the surface of the conveyor 6 and to the line of advance of strip b, with the consequence and effect that the grooved wheels 20 and the roller I are more eiiective in directing the strip a into desired assembly with strip b.

Advantageously, the grooved wheels or rollers .20 are severally mounted on blocks 2 I; the blocks 2| are carried on a rigid slide-bar 80 secured in the frame l8; and a screw shaft 23 extends through and in threaded engagement with the blocks. Outward from its center the shaft 23 is oppositely threaded, so that the interval between the two blocks may (by rotation of the shaft in one direction or the other) be varied, to adjust the rollers 20 for strips of different widths. A threaded shaft 24, mounted in the frame and engaging one of the blocks 2!, affords unit adjustment of the two blocks relatively to the center of the conveyor.

It will be understood that the surfaces of the extruded rubber strips a and b are tacky and sticky, as the surfaces of extruded rubber articles ordinarily are before final vulcanizing, and by virtue of such tackiness the two strips may be readily joined together and bonded, under the influence of applied pressure. My apparatus embodies particularly efiective means to this end.

More specifically, I provide a relatively narrow roller 9, a relatively wide roller II, and a pair of stitching wheels H, H. As the assembled strips a.

ing beneath the roller 9 are pinched and coming strips, and presses the central portion of strip 5 a into rubber-bonding engagement with the medial web 3b of strip b, it being noted that a rigid platen l2 (Fig. II) reinforces the upper reach of conveyor 8, so that the two bodies of rubber travelpressed in such manner as to effect the desired bond. As the two strips are thus brought to gether and by the roller 9 centrally united on an area of less width than the narrower strip, air is expelled laterally from between the strips. Upon moving from beneath the roller 9, the strips pass beneath roller l0. 'I'he'roller It consists in an assembly of metal disks Illa upon a shaft l3, and a pneumatic plunger P (Fig. II) is arranged to exert thrust on the shaft, forcing the disk roller into rubber-compressing contact with the strip a. Under the pressure of the roller disks Illa-a pressure effective on lines of contact rather than on a surface of contactall air remaining between strips is expelled and the bonding of the strips is completed across the entire width of the strip a. In such assembling and bonding of the strips, the cross-sectional shapes of the individual strips are modified. Before assembly and integration the strips have the cross-sectional shapes shown in Figs. VandVI, respectively, whereas after assembly the medial body portion of strip b and the lower body portion of strip a, having mutually yielded under the compression of rollers 9 and ID, are modified in form, as illustrated in Fig. IV. 3

Upon passing from the disk roller Hi, the assembled strips advance under the wheels II, II, and under the pressure of such wheels the opposite edges la of the strip a are securely'bonded or stitched, in closed pencil-line seams, to the 4 underlying body of the strip b. Each wheel is mounted on the distal end of an arm l4 secured to and extending from a rotary shaft l5 (Fig. II)

a bar l5 extends upward from the shaft l5, and, as shown, carries a weight I! which is effective 4 (through the shaft [5 and arms H) to press the wheels i I against the assembled strips. The arms II are adjustable axially of the shaft, to vary the interval between the stitching wheels for strips of various sizes.

As illustrated in Fig. IV, each wheel ll comprises a thin disk whose periphery is transversely curved on small radius; the wheels are inclinedat approximately 60 to the horizontal face of conveyor 8, and they are so positioned transversely of 5 the conveyor that their peripheries bear upon the edges la of the assembled strip a. and unite such edges to the strip 17. To the end that the seams shall be perfect, eliminating all crevices and fissures in which foreign particles might otherwise accumulate, two features of my invention are particularly important.

1. The opposite edges of the strip a are feathered; that is, the sides I a' of the strip are beveled downward and outward (Fig. V) fro-m the top surface t of the strip, and meet the nether surface 11. in thin, sharply defined edges 2a. The means for providing such feathered edges are described in application for Letters Patent, Serial No. 179,390, filed December 13, 1937, by Walter E. Humphrey, now Patent No. 2,218,751, dated October 22, 1940, and suflice it herein to say that a pair of knives 25 (Fig. I) is arranged at the mouth of the machine I, to trim terval between the ridges 2b on the strip b, so that in the assembled strips the feathered edges of strip a project laterally outward (in this case 152-") from the crests of said ridges on strip b.

By virtue of these two features, the stitching wheels II effect a perfect integration of the edges of strip a with the body of stripb. In

Fig. IV it will be perceived that the peripheries of the wheels II, rotating tangentially upon the advancing strip assembly a, I), press the feathered edges Ia into the surface of strip b, and stitch.

the edges Ia to the body of strip b in seams that extend parallel to, and lie laterally outward from, the crests of ridges 2*b. Thus, as shown in Fig. IV, the crests of the ridges 21; on the strip b are overlapped and enclosed by the feathered edges of strip a, whereby a perfect union of the two strips is obtained. It is impossible'for dust or other foreign particles to enter between the assembled strips. 1

Upon advancing from beneath the stitching wheels II, the strip assembly proceeds in uninterrupted course through a water bath 26 (Fig. I), over a conveyor 21 to scales 28, and from such scales to a conveyor 29,'whence it is led through a second water bath, or otherwise treated in accordance with recognized good practice, preparatory to its use in the construction of tires.

Thus, I form rubber of tough mix and rubber of elastic mixinto a composite strip for use in the construction of tires.

Those skilled in the art will understand that the extruding heads and dies of the extruding units I and 2 may be readily and quickly changed, and I have described the adjustability of the stitching wheels I I, I I and the strip-guiding rollers and wheels in frame I8. Manifestly, the apparatus is readily adaptable to the manufacture of strips for various sizes of tires. In the operation of such apparatus the method of the invention may be practised.

I claim as my invention:

1. Apparatus for the manufacture of a' composite strip of rubber, said apparatus including two units for severally extruding two rubbercompositions into two strips of complementary shapes, one relatively wide with respect to the other, means organized with one of said extruding units for feathering the side edges of the narrower strip, means for bringing the strips advancing severally from said extrudingunits into superposed relation, means arranged to exert on the advancing superposed strips a rubberbonding pressure for effecting integration of the bodies of the assembled strips on the area between the feathered edges of the narrower strip, and means for stitching said feathered edges of the narrower strip to the body of the wider strip.

2. The method of producing a composite strip of which to form the side-wall and tread of a tire, which method consists in shaping by extrusion the side-wall portion of the strip with lateral ridges and an intervening valley, forming by extrusion the tread portion of the strip with a width exceeding the space between the ridges in the side-wall portion, and feathering the side edges of said tread portion, assembling the two strip portions progressively, with the feathered edges of the tread portion positioned upon the ridges of the side-wall portion, and under rubber-bonding stress progressively pressing the tread portion into the valley between the ridges of said side-wall portion and shaping the body of such tread portion to the body of said sidewall portion within said valley, and then stitching the feathered edges of the tread portion over the crests of the ridges on the side-wall portion.

3. In apparatus ,for forming composite strip that goes to the making-up of the tread and sidewall of a drum-wheel tire, the combination of two rubber-extruding units provided with dies adapted to extrude to complementary shapes the tread portion and side-wall portion of said strip,

and means for progressively uniting the independently-formed portions of the strip comprising two endless traveling conveyors adapted to receive the strip portions severally from the extruding units and to advance said strip portions at substantially uniform velocity, one of said conveyors arranged above the other and adapted progressively to deliver the strip portion carried thereby downward and in longitudinally aligned position upon the strip portion advancing upon the other conveyor, two strip-aligning guides engaging the opposite side edges of the downwardly moving strip portion, said guides being adjustable transversely of the line of descent of the engaged strip and relatively to each other.

ARCHIIBALD C. BOWERS. 

